Rotary Tumble

Rotary Tumble is an experiment in projection mapping onto a moving tangible object. 

Rotary Tumble is an interactive audio-visual art installation that utilizes a freely spinning wheel as both display surface and as a tangible interface enabling users to interact with projected graphics. The installation enables users to spin the large wheel, and see how the projected graphics respond in real-time to the spinning. 

The wheel is used as a projection surface for the display of a real time physics simulation. The rotational speed and direction of the wheel is detected and used as input data to the physics simulation. As users spin the wheel, the physics simulation shows abstract objects tumbling inside the wheel, creating sounds when they collide. 

Rotary Tumble was created as an experiment in creating robust projection mapped interfaces that can survive being touched and used by thousands of visitors in gallery and public settings. We use a custom optical sensing mechanism that has no mechanical or moving parts to wear out. We detect the position, speed, and direction of spin by using a customized optical encoding wheel and simple computer vision system. The optical encoder consists of a video camera mounted behind the wheel looking at an encoder wheel pattern. This encoder is designed using "Gray Code", a special digital pattern ideal for optical tracking because its binary pattern only shifts one bit per increment. This property makes it well suited for use with a simple computer vision algorithm we built to read the Gray Code wheel printed on the back of the wheel.

System Diagram

Rotary Tumble consists of a flat wheel mounted to a solid shaft attached to two bearings atop a pedestal. Feedback from the optical sensor about the wheel's speed and direction is used to drive a physics simulation of basic tumbling shapes.  This simulation is then projected back onto the spinning disc itself. Basic projection mapping allows us to precisely match the simulation to the wheel shape. The physics simulator can detect the collisions between objects in the simulation. When these collisions occur, the simulator sends midi data to a synthesizer which creates a sound.

The resulting interactive installation is rather simple at first glance, but upon interacting with it, spinning the wheel, it comes to life. The physics parameters in the simulation are carefully tuned to match the scale and proportions of the physical disc, resulting in a natural realistic sensation. The sounds give the basic tumbling shapes a sense of solidity and resonance. The system blends the physical and the digital in a way that the mechanism is simultaneously input device and display.

Rotary Tumble has been installed in exhibition and event settings and has been used by thousands of visitors.

Shown and featured in the following exhibitions and books:

The 404 International Festival of Art and Technology, August 28 to August 31, Rosario, Argentina.

FILE - Electronic Language International Festival of electronic and digital technologies in the arts. Sao Paulo, Brazil 

Murano, Francesco (2014). LIGHT WORKS EXPERIMENTAL PROJECTION MAPPING. Aracne: isbn 978–88–548–7148–9